Whether "mankind makes it" in the end matters or not, our not making it would involve millennia of avoidable human suffering. It's a little hard to care about anything without caring about that, which I think is what your parent was getting at.

> not making it would involve millennia of avoidable human suffering

This premise assumes that in the situation where we "don't make it," the total amount of suffering by the end of the human race would be more than one in where we "do make it." Given that human suffering is caused by everything, I would say that if the race were to survive, there would be infinitely more suffering because we would have more time to inflict it. The premise seems to take for granted that the only way humans suffer is through harming our environment, which is of course not at all accurate. The only way to avoid human suffering is to immediately get rid of all humans; being in favor of existence, I have to argue that this is a fruitless position.

Likewise, if animals can suffer, then the existence of animals causes suffering. Animals attack each other, eat each other, steal each others' food source and offspring. The only way to prevent animal suffering is to have no animals. If plants can suffer, then the existence of plants causes suffering as they compete for sunlight and nutrients and the 'losers' wither and die.

I suppose my point is: any argument that involves potential existence causing suffering must ultimately come to these conclusions. I don't believe there is any other choice. Plants will never stop competing, animals will never stop competing, and humans will never stop competing.

Also, if the crux of your argument is avoidable human suffering, then I would be very interested to know what defines unavoidable human suffering.

[Just enjoying my Saturday morning by carrying out some debate]

I don't think I buy that the idea of "total amount of suffering" makes sense. That suggests that a world with more people, who are each suffering less, would be a worse world overall by virtue of having more "total" suffering. That strikes me as strongly counterintuitive, and very hard to justify rationally, though I'd be happy to see the attempt.

And in fact that seems to be the world we're living in. For example, in this TED talk[1] Steven Pinker makes the argument a person being born today — anywhere in the world, counting Iraq and Darfur — has less of a chance of dying at the hands of another person than at any time before in history.

So I'm a little skeptical of the idea that the only way to make the human race feel better is to have less of it.

[1] http://www.ted.com/talks/steven_pinker_on_the_myth_of_violen...

You are aware that mankind has subjected itself to avoidable suffering for as long as we could swing a stick, right? We have hundreds of millions suffering (avoidably might I add) right now and even if we somehow managed to keep Earth squeaky clean - I see a lot more avoidable suffering for the millennia to come.

If anything, significantly reducing Earth's capacity to sustain humans may paradoxically result in diminished total human suffering (average suffering x number of humans) due to lower population.

For what it's worth I do care, courtesy to my overly empathetic neural wiring. I'd argue that I am doing a lot more than my peers to reduce future human suffering simply by not contributing to the overpopulation. Not that any of it matters in the grand scheme of things ;)

Keep fighting the good fight, I admire your zeal!